Is there a limit with the number of sockets associated with the hosts you can monitor with the trial license?

I have 18 hosts in my environment each with two CPU sockets, and only 16 are being monitored. If I take a look at the server settings screen within Veeam One Monitor, the last two hosts are greyed out with 'excluded' next to them.

If I enable monitoring on those, I get a 'Licensed sockets number exceeded' error next to the host.